Disposable edge trimmers

I have gone through 3 Trimtech edge trimmers in 3 months. The first one just stopped working. I did not keep the slip so I could it exchange it. I went to buy a second one. It worked for less than a day and stopped working. I took it back to Builders and exchanged it. I asked them if I should use another brand or buy a better make. They assured me this one would be fine. The third one lasted a month. Builders now refuse to take it back. I am using the gut provided by Trimtech so can’t be overloading the machine. They last a few weeks and you need to get another one. They should be sold as disposable edge trimmers because that is exactly what they are.